The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
Selecting pollution control instruments is a crucial environmental policy decision, as evidenced in attempts to forge sovereign and global regulations pertaining to controls for greenhouse gas (“GHG”) emissions. However, in that case, debates among policy makers and critics have grown contentious due to fundamental disputes in public, private and academia sectors concerning the extent to which GHG (especially CO2) are global warming (“GW”) forces causing CC (hereafter referred to as “GHG Disputes”).
Extraordinarily high technology costs and long abatement periods exacerbate GHG Disputes. As a result, risks lurk that the United Nations Kyoto Protocol could fold barring a major turn of events. Due in part to those circumstances, a once-prominent GHG trading post (i.e., Chicago Climate Exchange) recently shuttered following nearly a decade of operations after trading volume plummeted and “carbon credit” (generic term for tradable certificates/permits holding the right to emit one metric tonne of CO2 or the mass of another GHG with a CO2 equivalent to one metric tonne of CO2) prices crashed 99% from their 2008 peaks.
In contrast, there are virtually no major disputes concerning benefits that can be realized by aggressively eliminating diesel PM. The market appears ripe for a global pollution control system based on the collection and eco-friendly recycling of captured agglomerated diesel soot (“CADS”), e.g., in the manner disclosed by in U.S. Ser. No. 61/531,126, assuming that financing mechanisms such as CADS Hybrids can gain traction over a suitable global market. U.S. application Ser. No. 61/531,126 is incorporated by reference as if fully set forth herein.
In some respects, incentive trade instruments employed to help curb GHG emissions in OECD countries, such as emission reduction credit (“ERC”) and capped allowance trading (“Cap-and-Trade”) systems, serve as trailblazers for the approach adopted in formulating CADS Hybrids. However, there is at least one major distinction: reducing GHG emissions in the OECD involves larger scale initiatives than those involved with abating the effects of super-emitters in countries compromised by needs to employ more affordably available but environmentally less desirable diesel fuels to power economic growth.
The former involves, inter alia, a myriad of extraordinarily costly and long term campaigns comprised of complex technology transformations, fuel conservation, displacement and replacement schemes, and related programs aimed as much at reducing reliance on fossil fuels as abating pollution levels. In fact, some GHG Disputes have involved heated debates as to whether CO2 should be treated as a pollutant.
The latter involves critical shorter term missions focused on DECAT technologies that are essentially already developed, are far less costly and merely require mobilization of forces to expedite mass implementation on a global scale. In fact, many leading scientists warn that time is of the essence to remove black carbon soot from the atmosphere; otherwise, tipping points could occur such that GHG reduction technologies on the drawing board may for all intents and purposes be rendered futile.
In terms of formulating a global pollution control system employing CADS Hybrids, pollution limits can in some cases be rate-based with no set limits on the maximum allowable level of pollution within the regulated area. Instead, pollution limits cannot exceed a specified rate of emissions (e.g., grams per mile or km for mobile vehicles; pounds or kg per MMBtu for power generators and stationary applications). Polluters can earn credits by employing qualified diesel emission control after-treatment (“DECAT”) systems designed to verifiably reduce emissions below specified rates. Having no cap on total emissions is appealing to policymakers in developing countries where anticipated economic growth is likely to occur alongside a corresponding increase in the number of individual polluters.
Alternatively, CADS Hybrid Cap-and-Trade systems can be formulated in a manner whereby allowable caps on total emissions are set, with a cap equal to the total number of allowances (permits) allocated to a group of polluters. Group allowances are then distributed among individual polluters. The number of allowances held by each polluter sets limits on levels they are entitled to emit. Allowances can be auctioned, with entities competing to purchase rights. Alternatively, they can be doled out as part of a government program. In any event, once all allowances are placed with rights holders, those entities must either reduce emissions directly or purchase allowances from other rights holders who achieve reductions below the required level.
Although not incorporated directly into the value of CADS Hybrids, other government policy tools are potentially useful as adjuncts to CADS Hybrid systems, such as: emissions taxes, fees and charges; subsidies; combining pollution standards with pricing approaches; and liability assignments.
Grants from sovereign and/or global regulatory bodies, as well as loans from entities dealing in concert with such bodies, can also play integral roles in the success of CADS Hybrid systems formulated.
While diesel-based pollution is without question a substantial global dilemma, pollution caused by the combustion of other major fuels is also troubling, and requires advanced remediation systems requiring sizable capital investments that can likewise be funded by the economic benefits derived from attendant recycling and other initiatives. For example, coal-based power systems have formed an essential part of economies around the world for many decades. Coal is an established electricity source that has provided vast quantities of relatively inexpensive, reliable power and, unfortunately, pollution. When coal is combusted in a furnace, boiler, etc., the ensuing heat is employed to generate steam used to spin one or more turbines to generate electricity.
When coal is combusted, however, significant amounts of residue are generated that require proper disposal or reuse. The largest volume of coal combustion residue consists of fly and bottom ash, along with boiler slag and flue gas desulfurization residue. Fly ash and bottom ash make up the majority. Although fly ash and bottom ash have similar origins, their physical and chemical characteristics differ. Fly ash is made up of relatively small particulate matter. The particulates have diameters typically ranging from 10 to 100 microns. The particulates may be captured and removed from flue (exhaust) gases by electrostatic precipitators, bag filters or other particle filtration equipment before the flue gases escape to the atmosphere via a chimney or stack. If fly ash escapes to the atmosphere, it can be extremely hazardous when inhaled, similar to what is experienced when black carbon soot is emitted by diesel engines.
The combination of black carbon soot emitted from diesel engines, along with fly ash escaping from coal-based power systems, is extremely hazardous, particularly in developing countries such as China. China is presently home to about half of the twenty most heavily polluted cities in the world, with some parts of the country exceeding “doomsday” levels of smoke pollution on an all-too regular basis. Reports published by the organization “Berkeley Earth” posit that air pollution kills an average of 4,000 people per day in China, accounting for 17% of all deaths in China. For about 38% of the Chinese population, the air they breathe is considered unhealthy by U.S. standards. According to a World Health Organization (“WHO”) report titled Global Burden of Disease, an estimated 1.2 million Chinese people died prematurely during 2010 due to air pollution, the vast majority of which was caused by the devastating aerosol cocktail of diesel related black carbon soot and coal-based fly ash.
Unlike fly ash, bottom ash adheres to hot sidewalls of coal combustion chambers during their operation, typically falling to the chamber's bottom hopper where it is ultimately cooled and removed. Bottom ash tends to consist of larger, coarser and heavier particles.
Coal ashes are mainly composed of oxides of silica, aluminum, iron, calcium, magnesium and sulfur. In addition to those macro-elements, coal ashes contain several trace elements including arsenic, selenium, boron, cadmium and lead. The concentration of trace elements in coal ashes can be enriched between 2 and 100 times relative to the original coal.
Chemical composition of the two ash types varies with age and maturity of the coal and its origin. For example, ashes from lignite and sub-bituminous coals contain more calcium and magnesium, which form basic solutions when mixed with water. Bituminous coal tends to contain more pyritic iron, resulting in acidic solutions when mixed with water. Concentrations of trace elements, such as arsenic and selenium, tend to be higher in fly ash than in bottom ash. And bituminous fly ash tends to have higher arsenic content than sub-bituminous and lignite coal ashes.
Each year, hundreds of millions of tons of coal combustion residue is produced throughout the world. Less than about 40% is currently used beneficially (i.e. recycled) and the remainder is disposed of in landfills, slurry retention ponds or minefills. Many of these locations are believed to be environmental “ticking time bombs”. Fly ash gets recycled more frequently than bottom ash; it's used in concrete to enhance strength and resistance to weathering. Other coal ash benefits include road-base materials, manufactured aggregates and land management uses like flowable fills, structural fills, soil embankments and soil modification materials.
Coal ash hazards stem from the physical properties of, and chemicals in, the ash. In addition to the aerosol issues disclosed above, fine particulate coal ash material can smother terrestrial vegetation and aquatic sediments in nearby rivers or ponds. Dry ash from ash piles not properly maintained pose health risks, particularly those attributable to particles less than 10 microns in diameter.
Although mercury's association with coal is well known, a large proportion of the mercury is vaporized during the combustion process; the remainder tends to be tightly bound to the captured ash particles and thus not released to the atmosphere. Other metals like lead and cadmium are also present at higher amounts in coal ash, with the latter being readily taken up by plants and thus placed into the food chain.
Chemical hazards in ash come from the coal combustion process and often include arsenic, selenium and boron. Because the mercury and chemical elements can be highly mobile in soils and sediments (especially those buried and saturated), they can leach out of ash piles and move into groundwater if pile impoundments are not properly lined. With bottom ash continually piling into landfills, risks associated with potable water contamination from ash leaching are growing substantially. Major disasters have occurred, such as in 2008 when Duke Energy's coal ash pond near Eden, Tenn. spilled hundreds of millions of gallons of contaminated water into the Dan River, which may end up costing cost Duke Energy billions of dollars in remediation and fines.
Municipal solid waste (“MSW”) incineration is another process which generates hundreds of millions of tons of refuse each year in the U.S., Europe and Asia. Approximately one-third of incinerated MSW ends up as ash. Incineration serves to concentrate toxic heavy metals normally present in MSW into resultant ash. As a result, MSW ash requires advanced treatment systems to reduce the quantity and mobility of heavy metals within the ash, including but not limited to stabilization, extraction, vitrification and solidification processes.
Waste-to-energy (“WTE”) combustion is another process which reduces the mass and volume of non-recyclable MSW refuse that would otherwise require landfilling. WTE combustion typically reduces the volume of MSW refuse by 90% and its solid mass by 70% to 80%. However, the resultant ash, while largely inert, contains concentrations of heavy metals that require advanced treatments to produce usable by-products and provide long-term stability of the metals in the event that the ash is exposed to the environment. Heavy metals such as lead and cadmium can be particularly toxic to biological systems when present in high enough concentrations.
Biomass Combustion is still another process which employs fuel in the form of plant matter (e.g. scrap lumber, forest debris, certain grasses and agricultural crops), manure and other biological material, including waste residues. Biomass is considered a renewable and sustainable source of energy because of the assumption that it will always exist. In industrialized countries, it is expected that the future generation of electricity will increasingly be derived from direct combustion of residues and wastes obtained from biomass.
Because of the high ash content inherent to biomass combustion systems (compared to that caused by burning coal and MSW), major challenges have arisen relating to the efficient management of their residues. Primary concerns involve storage, disposal and usage, as well as the presence of unburned carbon.
While coal, MSW and biomass fuels have been incinerated for decades to create meaningful heat and electricity alternatives to diesel and natural gas powered systems, new advanced thermo-chemical conversion (“TCC”) processes—along the lines of those previously disclosed here and U.S. Pat. No. 8,722,002, as it relates to CADS, offer significant advantages over mere incineration. To best understand those advantages, it is important to understand the significant differences between incineration and TCC. Incineration uses its respective source as a fuel, burning it with high volumes of air to form carbon dioxide and heat, with the heat used to make steam that is in turn used to help generate electricity while carbon dioxide escapes to the atmosphere. In addition, substantial amounts of insufficiently burned fly ash and bottom ash are created and captured in the process, most of which is not currently recycled, posing substantial hazards to humans, animals and the environment.
TCC systems similar to what has previously been disclosed in the case of CADS, particularly those employing gasification and/or pyrolysis, facilitate substantially less coal, MSW and biomass based pollutants to escape into the atmosphere. TCC systems, however, provide the benefit of producing valuable solid, liquid and gas by-products, and removing ash from landfill waste streams. This reduces methane emissions and leaching that would otherwise occur if this material were to enter already crowded landfills. Controlled TCC systems can also be integrated with carbon capture and storage systems to substantially eliminate carbon dioxide emissions.
Just as CADS can be recycled (per the disclosures of this invention and U.S. Pat. No. 8,722,002) into fullerenes, which are precursors for the synthesis of high value single walled carbon nanotubes, the recycling of ash and other residues generated by TCC of coal, MSW and biomass can also facilitate recovery of high value by-products including but not limited to rare earth elements (“REE”). As an example of the opportunities emerging in this field, the U.S. Department of Energy's National Energy Technology Laboratory announced on Dec. 2, 2015 that it had selected 10 projects in support of the lab's program on Recovery of REE from Coal and Coal Byproducts.
REE are a series of chemical elements found in the earth's crust. Due to their unique chemical properties, REE are components of many technologies spanning a range of applications, including electronics, computer and communications, transportation, healthcare, and national defense. The demand, cost and availability of REE have grown substantially over recent years, stimulating an emphasis on economically feasible approaches for REE recovery.
During the last 10 years, there has also been a substantial increase in the field of geopolymer science and technologies, with the number of scientific research papers exhibiting exponential growth. Geopolymers are inorganic materials that form long-range, covalently bonded, non-crystalline (amorphous) networks. Various geopolymers have been synthesized from coal fly ash, and to a lesser extent bottom ash.
Another example of high value materials recovered from ash involves commercial uses of geopolymers such as fire and heat resistant coatings and adhesives, medicinal applications, high temperature ceramics, new binders for fire resistant composites, toxic and radioactive waste encapsulation and as cementing components to make concrete. The properties and uses of geopolymers are being explored in many scientific and industrial disciplines, including modern inorganic chemistry physical chemistry, colloid chemistry, mineralogy, geology, and in other types of engineering process technologies.
Yet another example of high value materials recoverable from ash involves zeolites. Zeolites are crystalline aluminum silicates having a structure of tetrahides linked to each other at their corners, creating a three-dimensional network with lots of voids and open spaces that define their many special properties. Conventional open pit mining techniques are used to mine natural zeolites. Alternatively, industrially important zeolites can be synthesized from a wide variety of Si and Al starting materials, e.g., coal fly ash. Zeolites are commonly used as ion-exchange beds in domestic and commercial water purification and softening applications, as well as in commercial adsorbents and catalysts.
There is growing awareness that the types of recycling initiatives noted above can supply alternative materials capable of meeting the growing demand for naturally occurring resources, displacing the need to quarry or mine the naturally occurring resources, thereby offering substantial net marginal economic benefits. In addition, the types of TCC processes aimed at separating and removing metals such as lead and cadmium, as well as elements such as arsenic, selenium and boron, enhance proper land management practices aimed at reducing incidences of hazardous “leach out” of ash piles into groundwater.
All things considered, the timing is ripe for a new system that will help developing countries, as well as developed countries, proactively remediate local and global health, environmental and CC problems caused by diesel PM, as well as the hazardous byproducts of combusting other carbon containing feed materials including but not limited to coal, MSW and biomass.